Cutter for shaft and/or tunnel boring

ABSTRACT

A cutter is provided for shaft and/or tunnel boring which comprises a divided cutter ring ( 10   a,    10   b ) and a cutter body ( 8 ) with a recess ( 17 ). The cutter ring ( 10   a,    10   b ) is secured in the recess ( 17 ) by a divided clamping ring ( 18 ). The clamping ring ( 18 ) is divided into at least two segments ( 18   a,    18   b ) where each segment ( 18   a,    18   b ) has two segment ends, with the result that when the clamping ring ( 18 ) is tightened, a number of pairs of opposite segment ends are formed. Furthermore, in a tightened condition, all the pairs of opposite segment ends are either connected to securing elements ( 20 ), or, in a tightened condition, at least one pair of opposite segments ends is connected with a hinged device ( 19 ) while the remaining pairs of opposite segment ends are connected to securing elements ( 20 ). The segments ( 18   a,    18   b ) are tightened in the segments&#39; ( 18   a,    18   b ) circumferential direction.

The present invention relates to a cutter for shaft and/or tunnel boring, which cutter comprises a divided cutter ring which is secured to a cutter body by a clamping ring with at least two tightenable segments in a groove in the cutter body.

Today's cutter technology is based on the principle which has been employed for many years, where the cutter ring is shrunk on to the cutter body. Consequently the whole cutter has to be dismantled when the wear part, i.e. the cutter ring, has to be replaced. The tunnel boring machines have been improved and reinforced with a substantial increase in productivity, and the cutters have become larger with increased weight which places greater demands on the physique of the operators. There is a great need for an improvement in the cutter technology. The greatest potential for increasing productivity and reducing physical strain for the operators lies in the possibility of replacing the cutter ring when required without dismantling the actual cutter, and building a cutter which is so strong that a great many cutter rings can be worn out before the cutter has to be dismantled for maintenance.

Some solutions involving replaceable, divided cutter rings are known and have been tried, but have not been approved by the market.

One known method for tightening divided cutter rings is NO 314853 with a threaded clamping ring. The system requires a fixed point on the drill head for attaching an auxiliary tool, and it has been very difficult to loosen the clamping ring in order to replace the cutter ring.

Another known method is to use a divided clamping ring as described in the American patents U.S. Pat. No. 5,253,723 and U.S. Pat. No. 3,982,595. In these embodiments the clamping ring segments are attached to the cutter body by a number of radial bolts or screws.

The object of the present invention is to provide a cutter which permits fast and easy replacement of divided cutter rings by means of a reliable system for tightening and detaching the segments in the clamping ring and the cutter ring.

This is achieved according to the invention as it is defined in the independent claim 1. Further embodiments of the invention are specified in the dependent claims 2-10.

According to the invention there is a gap between the clamping ring's segments, thereby enabling them to be tightened and when released pushed apart by the same securing element by means of a back stop which restricts the return movement of the securing element. It supplies substantial forces which push the segments apart so that they are moved radially out from the groove, thereby neutralizing the frictional forces.

The invention also employs favourable flank angles in the groove in the cutter ring and sealing of the gap in the cutter ring in order to ensure correct positioning.

A cutter is thereby provided for shaft and/or tunnel boring comprising a divided cutter ring secured by a divided clamping ring in a recess in the cutter body. The clamping ring is divided into at least two segments, each with two segment ends. Between opposite segment ends there is a gap. In a tightened condition all the pairs of opposite segment ends are either connected to securing elements, or at least one pair of opposite segment ends is connected to a hinged device. The segments are tightened in the segments' circumferential direction.

In its simplest form the invention is provided with a two-part clamping ring, but it may also have more segments if required.

It is also possible to provide more than one divided cutter ring on the cutter and the cutter ring may be divided into more than two segments if this is expedient.

The recess in the cutter body where the segments of the cutter ring and the clamping ring are mounted preferably has greater depth for the clamping ring than for the cutter ring.

In one of the embodiments of the invention the securing element may be moved in a first direction to abut against a shoulder in one clamping ring segment for tightening to the second segment by means of a threaded bore. The securing element may also be moved in the opposite direction for abutment against a back stop in the first segment, thereby causing the segments to be pushed apart. The back stop may be in the form of back stop elements mounted on each side of a centre axis for the securing element.

The connecting elements may comprise a hinged device and/or securing elements. In an embodiment of the invention all the pairs of opposite clamping ring segment ends can be tightened by means of securing elements. In another embodiment of the invention at least one pair of opposite clamping ring segment ends can be connected by means of a hinged device while the rest are connected by means of securing elements.

A securing element may comprise a special screw element, a bolt or a similar securing device, mounted in one clamping ring segment for interaction with a threaded bore with a thread section in the second segment for tightening the two segments together. The securing element is provided with edges or ring surfaces, or possibly a head with an internal hexagon for interaction with the back stop.

In the recess in the cutter body the side wall which abuts against the cutter ring forms an angle a perpendicular to the cutter's centre line, the side wall which abuts against the clamping ring forms an angle c perpendicular to the cutter's axis of rotation, and the contact surface between the cutter ring and the clamping ring forms an angle b perpendicular to the cutter's axis of rotation. In an embodiment of the invention the cutter ring's adjacent angle a to the cutter body is preferably substantially greater than the adjacent angle c to the clamping ring, and the adjacent angle b is preferably equal to angle c and greater than the angle of friction for the contact surfaces.

The cutter body has one or more holes on the outside, thereby enabling the cutter to be rotated manually by placing a rod in the hole.

The invention and principal features and advantages thereof will become apparent from the patent claims and from the description of non-limiting embodiments presented below.

The invention will now be explained in greater detail with reference to the drawings in which

FIG. 1 illustrates current known cutter technology.

FIG. 2 illustrates an example of a cutter according to the invention.

FIGS. 3 a-c illustrate two examples of the clamping ring with securing elements and back stop therefor according to the invention.

FIG. 4 illustrates the use of the invention for a cutter with two cutter rings.

FIG. 1 illustrates current conventional cutter technology with a cutter ring A shrunk on to the cutter body B. The ends of a locking ring C are welded together after it is mounted in the groove D.

Since the cutter ring A is shrunk on to the cutter body B, it is necessary to dismantle the whole cutter when the cutter ring has to be replaced. It weighs over 100 kg. The drill head has to be rotated to enable lifting equipment to be used for the cutter which has to be replaced. Two men normally take 45 minutes for the actual cutter exchange. The cutter is transported to the workshop for cutter ring exchange and inspection which requires 1-2 working hours, whereupon the cutter is transported back to the tunnel boring machine. All of this can be avoided if the cutter ring can be replaced while the cutter is located on the drill head.

FIG. 2 illustrates a cutter designed according to the invention. The cutter has a shaft 1, roller bearings 2 and 3, end caps 4 and 5, rotating mechanical seals 6 and 7 and cutter body 8 with an undercut recess 17, in which are mounted a divided clamping ring with the segments 18 a, 18 b and a divided cutter ring with the segments 10 a, 10 b. The cutter body 8 has a number of holes 11 for a rod 12 which can be used to rotate the cutter manually.

The cutter ring's adjacent angle a to the cutter body 8 should preferably be greater than its adjacent angle b to the clamping ring.

FIGS. 3 a-b illustrate two embodiments of the clamping ring 18 which preferably consists of only two segments 18 a, 18 b. In FIG. 3 a the segments 18 a, 18 b are connected by a hinged device 19 at one end and drawn together to form a ring by means of a securing element which may be a specially designed screw 20.

At the rods 22, the screws are permanently but movably inserted in one segment 18 a. When the screw is tightened, the segments 18 a, 18 b, which are conically shaped in cross section, with the adjacent angles b and c, are pulled down into the gap formed between the cutter body 8 and the cutter ring segments 10 a, 10 b with oppositely located corresponding adjacent angles c and b (see FIG. 2). These adjacent angles should be greater than the angle of friction for the surfaces to enable them to be loosened without problems. The hinged device 19 may also be designed in a different way from that shown here, for example as a divided hinge capable of being hooked together, a chain link or the like. At the end of the opposite segment 18 b there is a threaded portion 23 intended to interact with the threaded portion G on the securing element 20. When the securing element 20 is tightened, the clamping ring segments 18 a, 18 b will push the cutter ring segments 10 a, 10 b with both radially as well as axially directed forces against the cutter body 8 (see FIG. 2). When the securing element 20 is rotated in the opposite direction, the securing element's head or the edge 24 will be pushed against the back stop 22 and the segments 18 a, 18 b will be pushed radially out from each other, thereby eliminating the frictional forces.

FIG. 3 b illustrates an embodiment where both ends of the clamping ring's segments 18 a, 18 b are tightened by means of securing elements 20, in this case special screws. The tightening and loosening are accomplished in the same way as described above in connection with the hinged clamping ring, the only difference being that the two segments 18 a, 18 b are connected by both the pairs of opposite segment ends by means of the securing elements 20.

FIG. 3 c illustrates three embodiments of clamping elements.

As illustrated in FIG. 4, two cutter rings with the segments 10 a, 10 b may be mounted on a cutter body. The same design of the clamping ring 18 is employed here as that described above. In this embodiment the two cutter rings are each mounted against a side edge of the recess 17, while the clamping ring with the segments 18 a, 18 b in the middle keep both the cutter rings in place in the recess.

The embodiments of the invention which are described above are provided with a two-part clamping ring 18. As described in the introduction, there is of course nothing to prevent the clamping ring 18 being provided with more than 2 segments.

With the design according to the present invention a new and easily-operated cutter is provided with a divided, replaceable cutter ring, which offers increased productivity and considerable labour saving. As will be apparent from the above description, the cutter is provided with components and details which both individually and together contribute to an excellent result. 

1. A cutter for shaft and/or tunnel boring, which cutter comprises a cutter body with a recess and at least one divided cutter ring which is secured in the recess by a clamping ring consisting of at least two segments, wherein the segments' ends, in a tightened condition, are tightened in pairs in the segments' circumferential direction by securing means provided at the end of the segments.
 2. A cutter according to claim 1, wherein all the segments' ends are tightened in pairs by securing elements arranged built into the end of the segments.
 3. A cutter according to claim 1, wherein between all opposite ends of the clamping ring's segments there is a gap for tightening.
 4. A cutter according to claim 1, wherein the securing means comprise at least one hinged device for connecting one end of the segments.
 5. A cutter according to claim 1, wherein the securing element can be moved in a first direction to abut against a shoulder in one clamping ring segment for tightening to the second segment and that the securing element can be moved in the opposite direction to abut against a back stop, with the result that the segments are pushed apart from each other.
 6. A cutter according to claim 2, wherein the back stop is in the form of back stop elements arranged on each side of a centre axis for the securing element.
 7. A cutter according to claim 1, wherein the securing means comprises a securing element in the form of a screw which is mounted built into one segment for interaction with a threaded section in the second segment for tightening of the two segments, and that the securing element is provided with edges or ring surfaces, or possibly a head, for interaction with the back stop in the first segment.
 8. A cutter according to claim 1, wherein the cutter ring segments' adjacent angle to the cutter body is preferably greater than the adjacent angle to the clamping ring, and that the adjacent angle is greater than the angle of friction for the contact surfaces.
 9. A cutter according to claim 1, wherein the cutter body is provided with one or more holes wherein a rod may be inserted, thereby enabling the cutter body to be rotated manually.
 10. A cutter according to claim 1, wherein the cutter body has 2 cutter rings with segments, both of which are secured on the cutter body by a divided clamping ring between the cutter rings. 